Device for controlling the sheet stack of a sheet processing machine



y 7, 1969 A. SCHWEBEL. 3,446,496

DEVICE FOR CONTROLLING THE SHEET STACK OI" A SHEET PROCESSING MACHINE Filed Feb. 2, 1967 Sheet of s lnven/or:

Filed Feb. 2, 1967 I May 27, 1969 A scHwEBEL 3,446,496

DEVICE FOR GQNTI iOLLING THE SHEET STACK OF A SHEET PROCESSING MA CHlNE Sheef. Z 01" s linen/01f:

mn-naws May 27, 1969 A. SCHWEBEL 6, 6

. DEVICE-FOR CONTROLLING THE SHEET STACK OF A SHEET PROCESSING MACHINE Filed F eb. 2, 1967 Sheet 3 of 5 lnven/or:

9pc; Stupi -Bl BY Mun (ad nail B vs United States Patent 3,446,496 DEVICE FOR CONTROLLING THE SHEET STACK OF A SHEET PROCESSING MACHINE Adolf Schwebel, Offenbach am Main, Germany, as-

signor to Mabeg Maschinenbau GmbH. Nachf, Hense & Pleines GmbH. & Co., Offenbach am Main, Germany, a firm of Germany Filed Feb. 2, 1967, Ser. No. 613,633 Int. Cl. B65h 1/08, 3/08 U.S. Cl. 271-31 7 Claims ABSTRACT OF THE DISCLOSURE The present invention relates to a device for supervising the up and down movement of a stack carrier of a sheet processing machine, and more particularly, to a switching device for limiting the stack lifting and lowering means to selected limit positions of the stack in either direction of movement of said means.

There are known switching devices to control the lifting of the sheet stack. Such devices include a limit switch which is opened by engagement with the top of the stack when the same is in a selected upper level position and thereby stops further lifting of the stack. Switching devices of this kind serve to prevent an overrunning of the sheet separating device, the sheet conveying devices and similar accessories to prevent damage to these rather generally expensive and delicate devicessThe danger of damage to the devices, is particularly great when the top surface of the stack is more uneven than usual and as a result is not engaged by a level probe usually provided to sto further lifting of the stack when the same reaches the level for which the probe is set.

Stack level control means of the kind hereinbefore referred to as now known, do not control the lowering movement of the sheet carrier and it is up to the service personnel to control and stop the downward movement of the stack carrier before the same strikes the floor.

There are also known stack level control devices which automatically check the downward movement of the stack carrier. Such control devices must be provided in addition to the afore referred to devices for controlling the upward movement of the stack. Obviously, the need for such further control devices increases the total cost of manufacturing and servicing the machine.

It is a broad object of the invention to provide a novel and improved supervisory device of the general kind above referred to in which the stack movement in both directions is supervised by a single switching means thereby correspondingly simplifying the machine and reducing the total costs thereof.

The afore pointed-out objects, features and advantages and other objects, features and advantages which will be hereinafter pointed out, are obtained by providing a multiple position switch which has a first position in which a reversible motor coupled to the stack carrier is connected for lifting the stack, a second position in which the motor is connected for lowering the stack and a third or OFF position in which the motor is disconnected. The switch has an upper level control arm which switches t e ice switch from the first position to the OFF position when' the top of the stack reaches a predetermined upper level and a lower level control arm which switches the switch from the second position to the OFF position when the top of the stack reaches a predetermined lower level. The lower level control arm is preferably coupled to transmission means connecting the motor to the stack carrier and is actuated when a selected moving part of the transmission means reaches a position which is indicative of the stack having reached its predetermined lower level position.

In the accompanying drawing several embodiments of the invention are shown by way of illustration and not by way of limitation.

FIG. 1 is an elevational diagrammatic view of a supervisory device according to the invention, the stack being shown close to its lower level position;

FIG. 2 is a diagrammatic elevational view of the supervisory device showing the same with the stack close to its upper level position;

FIG. 3 is a left hand side view of FIG. 2; and

FIG. 4 is an elevational diagrammatic view of the supervisory device including the circuitry therefor, the stack being shown close to its upper level position.

Referring now to the figures in detail, the device as exemplified in FIG. 1 comprises a stack carrier 3 supported by transmission means shown as chains or ropes 1 and 2. Carrier 3 supports a table 4 which, in turn, supports a sheet stack 5. The sheets are aligned or registered against guide edges 6. One or several devices 32 for separating and conveying the sheets are provided above the stack in a conventional manner. The entire stack assembly is guided by rollers 7 engaging a bracket 3a on the carrier. An adjustable set screw 8 the function of which will be more fully explained hereinafter may be provided on carrier 3.

The stack assembly as hereinbefore described should be visualized as being conventional and does not constitute part of the invention as such.

The supervision or control of the stack movements is effected by a multiple switching device 13 and a switching device 35. Switching device 13 comprises a control shaft 9 mounting an actuating means such as a handle 10 for turning the shaft. The shaft further mounts keyed thereto an arm 11a (see FIG. 3) supporting a roller 11, the arm and the roller constituting a limit switch for controlling the upper level position of the stack. The shaft also mounts a switch arm 12 engageable with switch contacts 14 and 15. These switch contacts should be visualized as being connected via conductors 16, 17 and 18 to a reversible drive motor 30 coupled to chains 1 and 2 via a shaft 38 and gears 39 for lifting and lowering the stack assembly and to a power main (not shown). The shaft 9 has also keyed thereto an arm 19 which is secured to one end of chain 2 of the transmission means, the chain being first guided downwardly, then upwardly about a pulley 37, then about one of gears 39 on motor shaft 38 and finally secured to bracket 3a of carrier 3. Chain 1 is secured on one end to bracket 3a and guided about the other gear 39, the other end of the chain hanging freely down as clearly shown.

A toggle spring 22 is secured at one end to a stationary part of the machine and at the other end to arm 12. This spring is so biased that it tends to turn switch arm 12 and also switch arm 11a into the horizontal position. As is clearly shown in this position the switch arm is out of engagement with either switch contact 14 and 15. This horizontal position constitutes the OFF position of switching device 13.

Placement of arm 12 in engagement with switch contact 14 energizes the drive motor for lowering the stack assembly, placement of the switch arm in engagement with switch contact energizes the motor for lifting the stack assembly and placement of the switch arm in the OFF position disconnects the motor. The required switching operations are effected by switching device 13. Switching devices capable of effecting the required switching operations are conventional and readily available in the market. They do not constitute part of the invention.

As is shown in FIGS. 2, 3, and 4, shaft 9 further has keyed thereto a control arm engageable with set screw 8 for switching the switching device to the OFF position when carrier 3 is lifted to a selected level as will be more fully described hereinafter. The device as hereinbefore described, operates as follows:

Let it be assumed that switch arm 12 is placed in the DOWN position as is shown in FIG. 1. The motor will then lower the stack assembly until it reaches a selected lower level position. In such position, the pull of chain 2 due to the downward movement of carrier 3 forces switch arm 12 out of its DOWN position via arm 19 and shaft 9 thereby causing toggle spring 22 to snap the switch arm into the OFF position thus causing the motor to stop.

In other words, chain portion 2 is so located and dimensioned that it will occupy a position causing stoppage of the motor when the stack assembly reaches the selected lower level position.

Similarly, placement of switch arm 12 in the UP position as is shown in FIG. 2 energizes the motor for lifting of the stack. When the top surface of the stack reaches a selected level it engages the limit switch 11, 11:: turning arm 11a and thus shaft 9 in clockwise direction thereby snapping the switch arm 12 from the UP position to the OFF position via shaft 9 so that the motor is stopped.

Control of the upward movement of the stack assembly by means of arm 20 is used when stack carrier 3 or table 4 is to be lifted for some operational reasons without a stack 5 placed thereon. As is evident, engagement of arm 20 with set screw 8 will snap switch arm 12 from the UP position to the OFF position via shaft 9.

The set screw 8 which can, of course, also be mounted on arm 20, permits a convenient adjustment of the level or the moment of time at which the upward movement of carrier 3 is stopped.

Turning now to FIG. 4, this for controlling the sheet feeder.

As shown, a third switch contact 28 is engaged by switch arm 12 in the OFF position thereof. Switch contact 28 is connected via a conductor 29 to one terminal of motor the other terminal of which is connected via the switching device and a conductor 31 to the power main. Switching device 35 comprises a stationary contact 27 and a movable contact 26 slideably engageable with contact 27. Contact 26 is adjustably supported by an arm 25 which, in turn, is supported by a probe 24 which continuously probes the top level of the stack by engaging the top sheet thereof.

Let it again be assumed that switch arm 12 is set in the UP position as is shown. The stack assembly is now lifted as previously described until limit switch 11, 11a assisted by spring 22 switches the switch arm into the OFF position. In this position one terminal of motor 30 is connected by switch contact 28 to the power main via conductors 17 and 29. The normal and conventional lifting speed of the stack matches the withdrawal speed of sheets.

Let it now be assumed that the stack is depleted by withdrawal of sheets by means of separating and conveying devices 32 faster than it is lifted. Probe 24 and with it arm 25 and contact 26, will follow the depletion of the stack. When the lag of the stack lifting is such that a stack level is reached at which switch contact 26 engages switch contact 27 the energizing circuit for motor 30 is completed via conductor 31 and the motor. The motor will now start thereby causing lifting of the stack figure shows the circuitry until contacts 26 and 27 become disengaged. Accordingly, the stack is lifted whenever such lifting is necessary to make up for withdrawal of sheets. In other words, switching device 13 when placed in the OFF position upon completion of a lifting or lowering ope-ration under the control of switch contacts 14 and 15 also controls intermittent or stepwise movements of the stack thereby eliminating the need for complex and expensive auxiliary power drives and simplifying the servicing of the machine. As a result, servicing of the machine and the costs thereof are correspondingly reduced.

While the invention has been described in detail with respect to certain now preferred examples and embodiments of the invention, it will be understood by those skilled in the art, after understanding the invention, that various changes and modifications may be made without departing from the spirit and scope of the invention, and it is intended, therefore to cover all such changes and modifications in the appended claims.

What is claimed is:

1. A device for limiting lifting and lowering of the sheet stack of a sheet processing machine, said device comprising in combination:

(a) a stack lifting and lowering assembly including a carrier for supporting a stack of sheets, reversible electrically operated drive means, and a mechanical transmission means actuated by the drive means and connected to said carrier for lifting and lowering the same in accordance with the driving direction of said drive means;

(b) multiple position limit switch means having a first switching position connecting the drive means for lifting the carrier, a second position connecting the drive means for lowering the carrier and a third switching position constituting an OFF position;

(c) a first detecting means coacting with said limit switch means and engageable with the top surface of a stack supported by said carrier for control by the level of said surface, said detecting means in response to said level reaching a selected upper level position moving said switch means from the first position to the OFF position; and

(d) a second detecting means coacting with said limit switch means and said transmission means for control by the same, said transmission means in response to a position thereof indicative of a selected lower level of the top surface of the stack actuating said second detecting means to move the switch means from the second position to the OFF position.

2. A device according to claim 1, wherein said limit switch means comprises a switch arm pivotal into any one of said three switching positions, said OFF position being lntermediate the first and the second switching position, and toggle spring means engaging said switch arm and disposed to bias the arm into the OFF position when the arm is moved out of the first or second switching position.

3. A device according to claim 1, wherein said first detecting means comprises a pivotally mounted probe coactmg with said limit switch means to switch the same, said probe engaging the top surface of the stack for pivoting by the same when the stack is being lifted, pivoting of the probe through an angle indicative of said selected upper level position of the top of the stack surface moving the switch means from the first switching position to the OFF position.

4. A device according to claim 1, wherein said mechanical transmission means comprises a movable member connected to said carrier, said second detecting means being connected to said movable member for switching the switch means from the second switching position to the OFF position when said movable member reaches a position in which the stack is in said selected lower level position.

5. A device according to claim 4, wherein said limit switch means comprises a rotatable shaft, a switch arm fixedly seated on said shaft for turning the switch arm into any one of said three switching positions by correspondingly rotating the shaft, and an actuating arm secured to said shaft, said arm being further secured to said movable member for turning the shaft and thus the switch arm into-the OFF position by movement of said member into the position in which the stack is in said selected lower level position.

6. A device according to claim 1 and comprising an electrically operated drive means for lifting the stack carrier, an energizing circuit for said drive means, a first normally open switch included in said energizing circuit, said switch being closed by said limit switch means in the OFF position thereof, a second normally open switch included in said energizing circuit, said second switch having a sta; tionary switch contact and a movable switch contact, and a movable third detecting means supporting said movable switch contact, said third detecting means engaging the top surface of the stack for detecting the level of said surface during lifting of the stack and moving said movable switch contact into engagement with the stationary contact when said surface is below a predetermined level during lifting of the stack thereby closing said second switch, simultaneous closing of said first and said second switch energizing said drive means for lifting the stack carrier until the surface of the stack thereon is at said predetermined glevel whereupon said second switch is opened by References Cited FOREIGN PATENTS 867,036 3/1961 Great Britain.

EDWARD A. SROKA, Primary Examiner.

US. Cl. X.R. 27l62 

